1. Field of the Invention
The technical field of the present invention relates to a semiconductor device which can transmit and receive data by wireless communication.
2. Description of the Related Art
In a wireless communication system using a radio frequency identification (RFID) technology, communication between a reader/writer and a non-contact data carrier is performed in such a manner that a carrier wave is transmitted from the reader/writer, electric power is supplied to the non-contact data carrier by electromagnetic induction, and the carrier wave is modulated.
The amount of electric power supplied from the reader/writer varies depending on the distance between an antenna of the reader/writer and an antenna of the non-contact data carrier. For example, when the non-contact data carrier and the reader/writer are in contact with each other, excessive electric power is supplied to an internal element of the non-contact data carrier. Accordingly, the non-contact data carrier cannot demodulate a signal from the reader/writer accurately, resulting in a problem of malfunction. In addition, there is a possibility that the internal element of the non-contact data carrier may deteriorate or be damaged.
As a countermeasure against such a problem, it is known that a protection circuit for protecting the internal element when excessive electric power is supplied to the non-contact data carrier is provided in the non-contact data carrier.
In Patent Document 1, an electric power transmission system and an IC card where electric power can be stably supplied even when the communication distance between a reader/writer and a non-contact data carrier is largely changed have been proposed.